US10630526B2 - Estimation apparatus for IQ imbalance of optical transmitter, compensation apparatus for IQ imbalance of optical transmitter and electronic equipment - Google Patents
Estimation apparatus for IQ imbalance of optical transmitter, compensation apparatus for IQ imbalance of optical transmitter and electronic equipment Download PDFInfo
- Publication number
- US10630526B2 US10630526B2 US16/163,975 US201816163975A US10630526B2 US 10630526 B2 US10630526 B2 US 10630526B2 US 201816163975 A US201816163975 A US 201816163975A US 10630526 B2 US10630526 B2 US 10630526B2
- Authority
- US
- United States
- Prior art keywords
- path
- received signals
- optical transmitter
- signals
- imbalance
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03D—DEMODULATION OR TRANSFERENCE OF MODULATION FROM ONE CARRIER TO ANOTHER
- H03D3/00—Demodulation of angle-, frequency- or phase- modulated oscillations
- H03D3/007—Demodulation of angle-, frequency- or phase- modulated oscillations by converting the oscillations into two quadrature related signals
- H03D3/009—Compensating quadrature phase or amplitude imbalances
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/50—Transmitters
- H04B10/501—Structural aspects
- H04B10/503—Laser transmitters
- H04B10/505—Laser transmitters using external modulation
- H04B10/5057—Laser transmitters using external modulation using a feedback signal generated by analysing the optical output
- H04B10/50572—Laser transmitters using external modulation using a feedback signal generated by analysing the optical output to control the modulating signal amplitude including amplitude distortion
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/60—Receivers
- H04B10/61—Coherent receivers
- H04B10/616—Details of the electronic signal processing in coherent optical receivers
- H04B10/6166—Polarisation demultiplexing, tracking or alignment of orthogonal polarisation components
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/0014—Carrier regulation
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/32—Carrier systems characterised by combinations of two or more of the types covered by groups H04L27/02, H04L27/10, H04L27/18 or H04L27/26
- H04L27/34—Amplitude- and phase-modulated carrier systems, e.g. quadrature-amplitude modulated carrier systems
- H04L27/36—Modulator circuits; Transmitter circuits
- H04L27/362—Modulation using more than one carrier, e.g. with quadrature carriers, separately amplitude modulated
- H04L27/364—Arrangements for overcoming imperfections in the modulator, e.g. quadrature error or unbalanced I and Q levels
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/32—Carrier systems characterised by combinations of two or more of the types covered by groups H04L27/02, H04L27/10, H04L27/18 or H04L27/26
- H04L27/34—Amplitude- and phase-modulated carrier systems, e.g. quadrature-amplitude modulated carrier systems
- H04L27/38—Demodulator circuits; Receiver circuits
- H04L27/3845—Demodulator circuits; Receiver circuits using non - coherent demodulation, i.e. not using a phase synchronous carrier
- H04L27/3854—Demodulator circuits; Receiver circuits using non - coherent demodulation, i.e. not using a phase synchronous carrier using a non - coherent carrier, including systems with baseband correction for phase or frequency offset
- H04L27/3863—Compensation for quadrature error in the received signal
Definitions
- This disclosure relates to the field of communications technologies, and in particular to an estimation apparatus for IQ imbalance of an optical transmitter, a compensation apparatus for IQ imbalance of an optical transmitter and electronic equipment.
- Coherent optical communications systems have developed rapidly in recent years due to their excellent anti-dispersion performance, the use of dispersion-free compensation optical fibers, and relatively high sensitivity of a receiver.
- it is generally required to provide a modulator in an optical transmitter to modulate a transmitted signal where in-phase and quadrature (IQ) modulators are widely used in optical communications systems to generate transmitted signals of high spectral efficiency.
- IQ in-phase and quadrature
- FIG. 1 is a schematic diagram of a modulator of an optical transmitter in the related art.
- a modulator 101 of the optical transmitter has two Mach-Zehnder modulators (MZMs), respectively referred to as a first Mach-Zehnder modulator 102 and a second Mach-Zehnder modulator 103 , and a phase modulator (PM) 104 , the first Mach-Zehnder modulator 102 and the second Mach-Zehnder modulator 103 being respectively used for modulating driving signals v rf,I and v rf,Q of an I path and a Q path, and the phase modulator 104 introducing a phase difference of 90° between the I path and the Q path.
- MZMs Mach-Zehnder modulators
- PM phase modulator
- bias voltages V I , V Q and V P on the three bias points, bias I, bias Q and bias P are controlled according to a result of detection of an output optical field of the modulator 101 .
- magnitudes of their relative power usually change at an output end of the modulator 101 , and such a change is referred to as IQ amplitude imbalance of the optical transmitter.
- FIG. 2 is a schematic diagram of the effect of the optical transmitter IQ imbalance on the constellation diagram of the received signals.
- the constellation diagram on the left side denotes the transmitted signals
- the constellation diagram on the right side denotes the received signals.
- the constellation diagram of the received signals at the receiver end becomes a distorted parallelogram.
- GSOP Gram-Schmidt orthogonalization
- a phase of the reference signal is easily influenced by an equalizer at receiving end and is inverse, and hence, an estimated direction of a phase offset drift is unstable. In addition, accuracy of its estimation of phase offset drift at larger angles is relatively poor.
- a constellation diagram of received signals may not be in parallel with a rectangular axis. That is, the existing method may also recover the distorted parallelogram constellation diagram on the right side in FIG. 2 into a square. However, a symmetry axis of the square may be offset from a symmetry axis of the constellation diagram of the transmitted signals, thereby resulting in a decision error.
- Embodiments of this disclosure provide an estimation apparatus for IQ imbalance of an optical transmitter, a compensation apparatus for IQ imbalance of an optical transmitter and electronic equipment. Estimation and compensation of IQ imbalance of an optical transmitter are performed by directly using an estimation model based on a transform matrix of received signals and transmitted signals, therefore, a phase offset shift may be estimated accurately, and precision of estimation of drifts of various angles is ensured, furthermore, accurate recovery of the constellation diagram of received signals is achieved.
- an estimation apparatus for IQ imbalance of an optical transmitter including: an acquiring unit configured to obtain I-path received signals and Q-path received signals at an optical receiver side; a coupling unit configured to perform alternating current (AC) coupling on the obtained I-path received signals and Q-path received signals; and an estimating unit configured to estimate the IQ imbalance of an optical transmitter on the AC coupled I-path received signals and Q-path received signals according to an estimation model based on a transform matrix of received signals and transmitted signals, the transform matrix including parameters related to an amplitude change and phase change of I-path transmitted signals and Q-path transmitted signals by the optical transmitter.
- AC alternating current
- a compensation apparatus for IQ imbalance of an optical transmitter including: the estimation apparatus for IQ imbalance of an optical transmitter as described in the first aspect of the embodiments of this disclosure; and a first compensating unit configured to, at an optical receiver end, compensate the IQ imbalance of the optical transmitter for the AC coupled I-path received signals and Q-path received signals according to an inverse matrix of the transform matrix, or, a second compensating unit configured to, at an optical transmitter end, pre-compensate for the I-path transmitted signals and Q-path transmitted signals according to at least one of a ratio of the amplitude changes of the I-path transmitted signals and the Q-path transmitted signals, a difference between the phase changes of the I-path transmitted signals and the Q-path transmitted signals and the transform matrix, the ratio and the difference being both obtained from the transform matrix.
- electronic equipment including: the estimation apparatus for IQ imbalance of an optical transmitter as described in the first aspect of the embodiments of this disclosure or the compensation apparatus for IQ imbalance of an optical transmitter as described in the second aspect of the embodiments of this disclosure.
- an estimation method for IQ imbalance of an optical transmitter including: obtaining I-path received signals and Q-path received signals at an optical receiver side; performing AC coupling on the obtained I-path received signals and Q-path received signals; and estimating the IQ imbalance of an optical transmitter on the AC coupled I-path received signals and Q-path received signals according to an estimation model based on a transform matrix of received signals and transmitted signals, the transform matrix including parameters related to an amplitude change and phase change of I-path transmitted signals and Q-path transmitted signals by the optical transmitter.
- a compensation method for IQ imbalance of an optical transmitter including: the estimation method for IQ imbalance of an optical transmitter as described in the fourth aspect of the embodiments of this disclosure; and at an optical receiver end, compensating the IQ imbalance of the optical transmitter for the AC coupled I-path received signals and Q-path received signals according to an inverse matrix of the transform matrix, or at an optical transmitter end, pre-compensating for the I-path transmitted signals and Q-path transmitted signals according to at least one of a ratio of the amplitude changes of the I-path transmitted signals and the Q-path transmitted signals, a difference between the phase changes of the I-path transmitted signals and the Q-path transmitted signals and the transform matrix, the ratio and the difference being both obtained from the transform matrix.
- An advantage of the embodiments of this disclosure exists in that estimation and compensation of IQ imbalance of an optical transmitter are performed by directly using an estimation model based on a transform matrix of received signals and transmitted signals, therefore, a phase offset shift may be estimated accurately, and precision of estimation of drifts of various angles is ensured, furthermore, accurate recovery of the constellation diagram of received signals is achieved.
- FIG. 1 is a schematic diagram of a modulator of an optical transmitter in the related art
- FIG. 2 is a schematic diagram of an effect of optical transmitter IQ imbalance on a constellation diagram of received signals
- FIG. 3 is a schematic diagram of the estimation apparatus for IQ imbalance of an optical transmitter of Embodiment 1 of this disclosure
- FIG. 4 is a schematic diagram of an estimating unit 303 of Embodiment 1 of this disclosure.
- FIG. 5 is a schematic diagram of a structure of a first estimating unit 401 of Embodiment 1 of this disclosure.
- FIG. 6 is a schematic diagram of a calculating unit 502 of Embodiment 1 of this disclosure.
- FIG. 7 is another schematic diagram of the calculating unit 502 of Embodiment 1 of this disclosure.
- FIG. 8 is a schematic diagram of a second estimating unit 402 of Embodiment 1 of this disclosure.
- FIG. 9 is a schematic diagram of a calculating module of a constant modulus algorithm or a radial orientation equalization algorithm of Embodiment 1 of this disclosure.
- FIG. 10 is a schematic diagram of the compensation apparatus for IQ imbalance of an optical transmitter of Embodiment 2 of this disclosure.
- FIG. 11 is a schematic diagram of the electronic equipment of Embodiment 3 of this disclosure.
- FIG. 12 is a block diagram of a systematic structure the electronic equipment of Embodiment 3 of this disclosure.
- FIG. 13 is a flowchart of the estimation method for IQ imbalance of an optical transmitter of Embodiment 4 of this disclosure.
- FIG. 14 is a flowchart of the compensation method for IQ imbalance of an optical transmitter of Embodiment 5 of this disclosure.
- terms “first”, and “second”, etc. are used to differentiate different elements with respect to names, and do not indicate spatial arrangement or temporal orders of these elements, and these elements should not be limited by these terms.
- Terms “and/or” include any one and all combinations of one or more relevantly listed terms.
- Terms “contain”, “include” and “have” refer to existence of stated features, elements, components, or assemblies, but do not exclude existence or addition of one or more other features, elements, components, or assemblies.
- single forms “a”, and “the”, etc. include plural forms, and should be understood as “a kind of” or “a type of” in a broad sense, but should not defined as a meaning of “one”; and the term “the” should be understood as including both a single form and a plural form, except specified otherwise.
- the term “according to” should be understood as “at least partially according to”, the term “based on” should be understood as “at least partially based on”, except specified otherwise.
- FIG. 3 is a schematic diagram of the estimation apparatus for IQ imbalance of an optical transmitter of Embodiment 1 of this disclosure. As shown in FIG. 3 , an estimation apparatus 300 includes:
- an acquiring unit 301 configured to obtain -path received signals and Q-path received signals at an optical receiver side;
- a coupling unit 302 configured to perform AC coupling on the obtained I-path received signals and Q-path received signals
- an estimating unit 303 configured to estimate the IQ imbalance of an optical transmitter on the AC coupled I-path received signals and Q-path received signals according to an estimation model based on a transform matrix of received signals and transmitted signals, the transform matrix including parameters related to an amplitude change and phase change of I-path transmitted signals and Q-path transmitted signals by the optical transmitter.
- estimation and compensation of IQ imbalance of an optical transmitter are performed by directly using an estimation model based on a transform matrix of received signals and transmitted signals, therefore, a phase offset shift may be estimated accurately, and precision of estimation of drifts of various angles is ensured, furthermore, accurate recovery of the constellation diagram of received signals is achieved.
- the acquiring unit 301 may obtain I path received signals and Q path received signals by using an existing method.
- coherent detection, analog-to-digital conversion and constellation diagram recovery may be performed on I path received signals and Q path received signals at an optical receiver end.
- the constellation diagram recovery may include IQ imbalance compensation, resampling, channel equalization and carrier phase recovery at the receiver end.
- the coupling unit 302 is configured to perform AC coupling on the obtained I path received signals and Q path received signals, to remove an effect of DC offset drift of a modulator in the optical transmitter.
- the estimating unit 303 is configured to estimate the IQ imbalance of the optical transmitter on the AC coupled I-path received signals and Q-path received signals according to the estimation model based on the transform matrix of the received signals and transmitted signals, the transform matrix including the parameters related to the amplitude change and phase change of the I-path transmitted signals and Q-path transmitted signals by the optical transmitter.
- (I 1 , Q 1 ) denotes the received signals
- (I 0 , Q 0 ) denotes the transmitted signals
- a and b respectively denote values of the amplitude changes of the I-path transmitted signals and Q-path transmitted signals by the optical transmitter
- ⁇ i and ⁇ Q respectively denote values of the phase changes of the I-path transmitted signals and Q-path transmitted signals by the optical transmitter.
- (I 1 , Q 1 ) denotes the received signals
- (I 0 , Q 0 ) denotes the transmitted signals
- a and b respectively denote values of the amplitude changes of the I-path transmitted signals and Q-path transmitted signals by the optical transmitter
- ⁇ I and ⁇ Q respectively denote values of the phase changes of the I-path transmitted signals and Q-path transmitted signals by the optical transmitter
- C denotes a transform matrix.
- transform matrix C includes parameters related to the values of the amplitude changes b and a and phase changes ⁇ I and ⁇ Q of I-path transmitted signals and Q-path transmitted signals by the optical transmitter.
- the estimating unit 303 estimates the IQ imbalance of an optical transmitter on the AC coupled I-path received signals and Q-path received signals according to the estimation model based on the transform matrix of the received signals and transmitted signals. For example, the estimating unit 303 estimates transform matrix C, and hence, the parameters characterizing the IQ imbalance of an optical transmitter may be obtained.
- a structure of the estimating unit 303 and a method for estimating the IQ imbalance of an optical transmitter shall be illustrated below.
- FIG. 4 is a schematic diagram of the estimating unit 303 of Embodiment 1 of this disclosure. As shown in FIG. 4 , the estimating unit 303 includes:
- a first estimating unit 401 configured to estimate the IQ imbalance of an optical transmitter on the AC coupled I-path received signals and Q-path received signals based on a training sequence
- a second estimating unit 402 configured to estimate the IQ imbalance of an optical transmitter on the AC coupled I-path received signals and Q-path received signals based on a blind estimation method.
- FIG. 5 is a schematic diagram of a structure of the first estimating unit 401 of Embodiment 1 of this disclosure. As shown in FIG. 5 , the first estimating unit 401 includes:
- a synchronizing unit 501 configured to synchronize the AC coupled I-path received signals and Q-path received signals with the training sequence
- a calculating unit 502 configured to calculate the transform matrix according to the synchronized I-path received signals and Q-path received signals and the training sequence.
- the first estimating unit 401 estimates the IQ imbalance of an optical transmitter on the AC coupled I-path received signals and Q-path received signals based on the training sequence, the training sequence being constituted by constellation points of the transmitted signals. For example, as shown in FIG. 2 , at least 4 constellation groups may be selected from 16 constellation groups and taken as the training sequence.
- the calculating unit 502 calculates the transform matrix according to the synchronized I-path received signals and Q-path received signals and the training sequence.
- FIG. 6 is a schematic diagram of the calculating unit 502 of Embodiment 1 of this disclosure. As shown in FIG. 6 , the calculating unit 502 includes:
- a first forming unit 601 configured to make central points of constellation groups of constellation diagrams of the synchronized I-path received signals and Q-path received signals form a received constellation matrix
- a second forming unit 602 configured to make training symbols in the training sequence corresponding to the central points of constellation groups form a reference matrix
- a first calculating unit 603 configured to calculate the transform matrix according to the received constellation matrix and the reference matrix.
- the first form unit 601 makes the central points of constellation groups of the constellation diagram of the synchronized I-path received signals and Q-path received signals form a received constellation matrix
- the second forming unit 602 makes the training symbols in the training sequence corresponding to the central points of constellation groups form a reference matrix
- N denoting a length of the training sequence, i.e. the number of training symbols in the training sequence, and the first calculating unit 603 calculates the transform matrix C according to the received constellation matrix
- FIG. 7 is another schematic diagram of the calculating unit 502 of Embodiment 1 of this disclosure. As shown in FIG. 7 , the calculating unit 502 includes:
- a second calculating unit 701 configured to calculate the transform matrix by using a minimum mean square error criterion according to the synchronized I-path received signals and Q-path received signals and the training sequence.
- the second calculating unit 701 calculates the matrix C by using a minimum mean square error criterion according to the received constellation matrix
- N denotes the reference matrix
- N denotes the length of the training sequence
- ( ⁇ ) r denotes a transposition operation of the matrix
- ( ⁇ ) ⁇ 1 denotes an inverse operation of the matrix.
- the second estimating unit 402 estimates the IQ imbalance of an optical transmitter on the AC coupled I-path received signals and Q-path received signals based on the blind estimation method.
- FIG. 8 is a schematic diagram of the second estimating unit 402 of Embodiment 1 of this disclosure. As shown in FIG. 8 , the second estimating unit 402 includes:
- a third estimating unit 801 configured to, for transmitted signals of a constant modulus modulation format, calculate the transform matrix by using a constant modulus algorithm according to the AC coupled I-path received signals and Q-path received signals; and a fourth estimating unit 802 configured to, for transmitted signals of a non-constant modulus modulation format, calculate the transform matrix by using a radial orientation equalization algorithm according to the AC coupled I-path received signals and Q-path received signals.
- the third estimating unit 801 and the fourth estimating unit 802 may calculate the transform matrix by using existing constant modulus algorithm and radial orientation equalization algorithm.
- FIG. 9 is a schematic diagram of a calculating module of the constant modulus algorithm or the radial orientation equalization algorithm of Embodiment 1 of this disclosure.
- h II , h QI , h IQ , and h QQ are four real number filters in a calculating module 900 , and each of them has only one tap.
- An error is calculated by using the constant modulus algorithm or the radial orientation equalization algorithm and is inputted into an updating unit 901 to update tap coefficients of the four filters. And when the tap coefficients converge, the transform matrix
- estimation and compensation of IQ imbalance of an optical transmitter are performed by directly using an estimation model based on a transform matrix of received signals and transmitted signals, therefore, a phase offset shift may be estimated accurately, and precision of estimation of drifts of various angles is ensured, furthermore, accurate recovery of the constellation diagram of received signals is achieved.
- FIG. 10 is a schematic diagram of the compensation apparatus for IQ imbalance of an optical transmitter of Embodiment 2 of this disclosure.
- a compensation apparatus 1000 includes:
- a first compensating unit 1002 configured to, at an optical receiver end, compensate the IQ imbalance of the optical transmitter for the AC coupled I-path received signals and Q-path received signals according to an inverse matrix of the transform matrix
- a second compensating unit 1003 configured to, at an optical transmitter end, pre-compensate for the I-path transmitted signals and Q-path transmitted signals according to at least one of a ratio of the amplitude changes of the I-path transmitted signals and the Q-path transmitted signals, a difference between the phase changes of the I-path transmitted signals and the Q-path transmitted signals and the transform matrix.
- the estimation apparatus 1001 for IQ imbalance of an optical transmitter is identical to that described in Embodiment 1, and shall not be described herein any further.
- the first compensating unit 1002 configured to, at the optical receiver end, compensate the IQ imbalance of the optical transmitter for the AC coupled I-path received signals and Q-path received signals according to the inverse matrix of the transform matrix.
- the first compensating unit 1002 transforms the AC coupled I-path received signals and Q-path received signals by directly using an inverse matrix C ⁇ 1 of the transform matrix C, to obtain compensated I-path received signals and Q-path received signals.
- the second compensating unit 1003 configured to, at the optical transmitter end, pre-compensate for the I-path transmitted signals and Q-path transmitted signals according to at least one of the ratio of the amplitude changes of the I-path transmitted signals and the Q-path transmitted signals obtained from the transform matrix, the difference between the phase changes of the I-path transmitted signals and the Q-path transmitted signals and the transform matrix.
- the second compensating unit 1003 pre-compensates for the I-path transmitted signals and Q-path transmitted signals according to at least one or me ratio
- the second compensating unit 1003 performs compensation for the amplitude imbalance by using a matrix
- estimation and compensation of IQ imbalance of an optical transmitter are performed by directly using an estimation model based on a transform matrix of received signals and transmitted signals, therefore, a phase offset shift may be estimated accurately, and precision of estimation of drifts of various angles is ensured, furthermore, accurate recovery of the constellation diagram of received signals is achieved.
- FIG. 11 is a schematic diagram of the electronic equipment of Embodiment 3 of this disclosure.
- electronic equipment 1100 includes an estimation apparatus 1101 for IQ imbalance of an optical transmitter or a compensation apparatus 1102 for IQ imbalance of an optical transmitter.
- the estimation apparatus 1101 for IQ imbalance of an optical transmitter and the compensation apparatus 1102 for IQ imbalance of an optical transmitter are identical to those described in embodiments 1 and 2, and shall not be described herein any further.
- the electronic equipment may be a stand-alone device, or may be integrated into an optical receiver or an optical transmitter.
- FIG. 12 is a block diagram of a systematic structure the electronic equipment of Embodiment 3 of this disclosure.
- electronic equipment 1200 may include a processor 1210 and a memory 1220 , the memory 1220 being coupled to the processor 1210 .
- the memory 1220 may store various data, and furthermore, it may store a program 1221 for information processing, and execute the program 1221 under control of the processor 1210 .
- functions of the estimation apparatus 1101 may be integrated into the processor 1210 .
- the processor 1210 may be configured to: obtain I-path received signals and Q-path received signals at an optical receiver side; perform AC coupling on the obtained I-path received signals and Q-path received signals; and estimate the IQ imbalance of an optical transmitter on the AC coupled I-path received signals and Q-path received signals according to an estimation model based on a transform matrix of received signals and transmitted signals, the transform matrix including parameters related to an amplitude change and phase change of I-path transmitted signals and Q-path transmitted signals by the optical transmitter.
- the estimating the IQ imbalance of an optical transmitter on the AC coupled I-path received signals and Q-path received signals includes: estimating the IQ imbalance of an optical transmitter on the AC coupled I-path received signals and Q-path received signals based on a training sequence.
- the estimating the IQ imbalance of an optical transmitter on the AC coupled I-path received signals and Q-path received signals based on a training sequence includes: synchronizing the AC coupled I-path received signals and Q-path received signals with the training sequence; and calculating the transform matrix according to the synchronized I-path received signals and Q-path received signals and the training sequence.
- the calculating the transform matrix according to the synchronized I-path received signals and Q-path received signals and the training sequence includes: making central points of constellation groups of constellation diagrams of the synchronized I-path received signals and Q-path received signals form a received constellation matrix; making training symbols in the training sequence corresponding to the central points of constellation groups form a reference matrix; and calculating the transform matrix according to the received constellation matrix and the reference matrix.
- the calculating the transform matrix according to the synchronized I-path received signals and Q-path received signals and the training sequence includes: calculating the transform matrix by using a minimum mean square error criterion according to the synchronized I-path received signals and Q-path received signals and the training sequence.
- the estimating the IQ imbalance of an optical transmitter on the AC coupled I-path received signals and Q-path received signals includes: estimating the IQ imbalance of an optical transmitter on the AC coupled I-path received signals and Q-path received signals based on a blind estimation method.
- the estimating the IQ imbalance of an optical transmitter on the AC coupled I-path received signals and Q-path received signals based on a blind estimation method includes: for transmitted signals of a constant modulus modulation format, calculating the transform matrix by using a constant modulus algorithm according to the AC coupled I-path received signals and Q-path received signals; and for transmitted signals of a non-constant modulus modulation format, calculating the transform matrix by using a radial orientation equalization algorithm according to the AC coupled I-path received signals and Q-path received signals.
- functions of the compensation apparatus 1102 may be integrated into the processor 1210 .
- the processor 1210 may further be configured to: compensate the IQ imbalance of the optical transmitter for the AC coupled I-path received signals and Q-path received signals according to an inverse matrix of the transform matrix; or, at an optical transmitter end, pre-compensate for the I-path transmitted signals and Q-path transmitted signals according to at least one of a ratio of the amplitude changes of the I-path transmitted signals and the Q-path transmitted signals, a difference between the phase changes of the I-path transmitted signals and the Q-path transmitted signals and the transform matrix, the ratio and the difference being both obtained from the transform matrix.
- estimation apparatus 1101 or the compensation apparatus 1102 and the central processing unit 401 and the processor 1210 may be configured separately.
- the estimation apparatus 1101 or the compensation apparatus 1102 may be configured as a chip connected to the processor 1210 , with its functions being realized under control of the processor 1210 .
- the electronic equipment 1200 may further include an input/output (I/O) device 1230 , etc.
- I/O input/output
- functions of above components are similar to those in the related art, and shall not be described herein any further.
- the electronic equipment 1200 does not necessarily include all parts shown in FIG. 12 , and furthermore, the electronic equipment 1200 may include parts not shown in FIG. 12 , and the related art may be referred to.
- estimation and compensation of IQ imbalance of an optical transmitter are performed by directly using an estimation model based on a transform matrix of received signals and transmitted signals, therefore, a phase offset shift may be estimated accurately, and precision of estimation of drifts of various angles is ensured, furthermore, accurate recovery of the constellation diagram of received signals is achieved.
- the embodiment of this disclosure provides an estimation method for IQ imbalance of an optical transmitter, corresponding to the estimation apparatus for IQ imbalance of an optical transmitter in Embodiment 1.
- FIG. 13 is a flowchart of the estimation method for IQ imbalance of an optical transmitter of Embodiment 4 of this disclosure. The method includes:
- Step 1301 I-path received signals and Q-path received signals are obtained at an optical receiver side;
- Step 1302 AC coupling is performed on the obtained I-path received signals and Q-path received signals.
- Step 1303 the IQ imbalance of an optical transmitter is estimated on the AC coupled I-path received signals and Q-path received signals according to an estimation model based on a transform matrix of received signals and transmitted signals, the transform matrix including parameters related to an amplitude change and phase change of I-path transmitted signals and Q-path transmitted signals by the optical transmitter.
- estimation and compensation of IQ imbalance of an optical transmitter are performed by directly using an estimation model based on a transform matrix of received signals and transmitted signals, therefore, a phase offset shift may be estimated accurately, and precision of estimation of drifts of various angles is ensured, furthermore, accurate recovery of the constellation diagram of received signals is achieved.
- the embodiment of this disclosure provides a compensation method for IQ imbalance of an optical transmitter, corresponding to the compensation apparatus for IQ imbalance of an optical transmitter in Embodiment 2.
- FIG. 14 is a flowchart of the compensation method for IQ imbalance of an optical transmitter of Embodiment 5 of this disclosure. The method includes:
- Step 1401 I-path received signals and Q-path received signals are obtained at an optical receiver side:
- Step 1402 AC coupling is performed on the obtained I-path received signals and Q-path received signals;
- Step 1403 the IQ imbalance of an optical transmitter is estimated on the AC coupled I-path received signals and Q-path received signals according to an estimation model based on a transform matrix of received signals and transmitted signals, the transform matrix including parameters related to an amplitude change and phase change of I-path transmitted signals and Q-path transmitted signals by the optical transmitter;
- Step 1404 at an optical receiver end, the IQ imbalance of the optical transmitter is compensated for the AC coupled I-path received signals and Q-path received signals according to an inverse matrix of the transform matrix; or,
- Step 1405 at an optical transmitter end, the I-path transmitted signals and Q-path transmitted signals are pre-compensated according to at least one of a ratio of the amplitude changes of the I-path transmitted signals and the Q-path transmitted signals, a difference between the phase changes of the I-path transmitted signals and the Q-path transmitted signals and the transform matrix, the ratio and the difference being both obtained from the transform matrix.
- estimation and compensation of IQ imbalance of an optical transmitter are performed by directly using an estimation model based on a transform matrix of received signals and transmitted signals, therefore, a phase offset shift may be estimated accurately, and precision of estimation of drifts of various angles is ensured, furthermore, accurate recovery of the constellation diagram of received signals is achieved.
- An embodiment of the present disclosure provides a computer readable program, which, when executed in an estimation apparatus for IQ imbalance of an optical transmitter or electronic equipment, will cause the estimation apparatus for IQ imbalance of an optical transmitter or the electronic equipment to carry out the estimation method for IQ imbalance of an optical transmitter as described in Embodiment 3.
- An embodiment of the present disclosure provides a computer readable program, which, when executed in a compensation apparatus for IQ imbalance of an optical transmitter or electronic equipment, will cause the compensation apparatus for IQ imbalance of an optical transmitter or the electronic equipment to carry out the compensation method for IQ imbalance of an optical transmitter as described in Embodiment 4.
- An embodiment of the present disclosure provides a computer storage medium, including a computer readable program, which will cause an estimation apparatus for IQ imbalance of an optical transmitter or electronic equipment to carry out the estimation method for IQ imbalance of an optical transmitter as described in Embodiment 3.
- An embodiment of the present disclosure provides a computer storage medium, including a computer readable program, which will cause a compensation apparatus for IQ imbalance of an optical transmitter or electronic equipment to carry out the compensation method for IQ imbalance of an optical transmitter as described in Embodiment 4.
- the estimation method for IQ imbalance of an optical transmitter or the compensation method for IQ imbalance of an optical transmitter carried out in the estimation apparatus for IQ imbalance of an optical transmitter, or the compensation apparatus for IQ imbalance of an optical transmitter, or the electronic equipment, described with reference to the embodiments of this disclosure, may be directly embodied as hardware, software modules executed by a processor, or a combination thereof.
- one or more functional block diagrams and/or one or more combinations of the functional block diagrams shown in FIG. 3 or FIG. 10 may either correspond to software modules of procedures of a computer program, or correspond to hardware modules.
- Such software modules may respectively correspond to the steps shown in FIGS. 13 and 14 .
- the hardware module for example, may be carried out by firming the soft modules by using a field programmable gate array (FPGA).
- FPGA field programmable gate array
- the soft modules may be located in an RAM, a flash memory, an ROM, an EPROM, and an EEPROM, a register, a hard disc, a floppy disc, a CD-ROM, or any memory medium in other forms known in the art.
- a memory medium such as a non-transitory storage medium, may be coupled to a processor, so that the processor may be able to read information from the memory medium, and write information into the memory medium; or the memory medium may be a component of the processor.
- the processor and the memory medium may be located in an ASIC.
- the soft modules may be stored in a memory of a mobile terminal, and may also be stored in a memory card of a pluggable mobile terminal.
- the soft modules may be stored in the MEGA-SIM card or the flash memory device of a large capacity.
- One or more functional blocks and/or one or more combinations of the functional blocks in FIG. 3 and FIG. 10 may be realized as a universal processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware component or any appropriate combinations thereof carrying out the functions described in this application.
- DSP digital signal processor
- ASIC application-specific integrated circuit
- FPGA field programmable gate array
- the one or more functional block diagrams and/or one or more combinations of the functional block diagrams in the accompanying drawings may also be realized as a combination of computing equipment, such as a combination of a DSP and a microprocessor, multiple processors, one or more microprocessors in communications combination with a DSP, or any other such configuration.
- An estimation apparatus for IQ imbalance of an optical transmitter including:
- an acquiring unit configured to obtain I-path received signals and Q-path received signals at an optical receiver side
- a coupling unit configured to perform AC coupling on the obtained I-path received signals and Q-path received signals
- an estimating unit configured to estimate the IQ imbalance of an optical transmitter on the AC coupled I-path received signals and Q-path received signals according to an estimation model based on a transform matrix of received signals and transmitted signals, the transform matrix including parameters related to an amplitude change and phase change of I-path transmitted signals and Q-path transmitted signals by the optical transmitter.
- a first estimating unit configured to estimate the IQ imbalance of an optical transmitter on the AC coupled I-path received signals and Q-path received signals based on a training sequence.
- a synchronizing unit configured to synchronize the AC coupled I-path received signals and Q-path received signals with the training sequence
- a calculating unit configured to calculate the transform matrix according to the synchronized I-path received signals and Q-path received signals and the training sequence.
- a first forming unit configured to make central points of constellation groups of constellation diagrams of the synchronized I-path received signals and Q-path received signals form a received constellation matrix
- a second forming unit configured to make training symbols in the training sequence corresponding to the central points of constellation groups form a reference matrix
- a first calculating unit configured to calculate the transform matrix according to the received constellation matrix and the reference matrix.
- a second calculating unit configured to calculate the transform matrix by using a minimum mean square error criterion according to the synchronized I-path received signals and Q-path received signals and the training sequence.
- a second estimating unit configured to estimate the IQ imbalance of an optical transmitter on the AC coupled I-path received signals and Q-path received signals based on a blind estimation method.
- a third estimating unit configured to, for transmitted signals of a constant modulus modulation format, calculate the transform matrix by using a constant modulus algorithm according to the AC coupled I-path received signals and Q-path received signals; and a fourth estimating unit configured to, for transmitted signals of a non-constant modulus modulation format, calculate the transform matrix by using a radial orientation equalization algorithm according to the AC coupled I-path received signals and Q-path received signals.
- a compensation apparatus for IQ imbalance of an optical transmitter including:
- a first compensating unit configured to, at an optical receiver end, compensate the IQ imbalance of the optical transmitter for the AC coupled I-path received signals and Q-path received signals according to an inverse matrix of the transform matrix
- a second compensating unit configured to, at an optical transmitter end, pre-compensate for the I-path transmitted signals and Q-path transmitted signals according to at least one of a ratio of the amplitude changes of the I-path transmitted signals and the Q-path transmitted signals, a difference between the phase changes of the I-path transmitted signals and the Q-path transmitted signals and the transform matrix, the ratio and the difference being both obtained from the transform matrix.
- Supplement 10 Electronic equipment, including the estimation apparatus for IQ imbalance of an optical transmitter as described in any one of supplements 1-8, or the compensation apparatus for IQ imbalance of an optical transmitter as described in supplement 9.
- An estimation method for IQ imbalance of an optical transmitter including:
- the IQ imbalance of an optical transmitter on the AC coupled I-path received signals and Q-path received signals according to an estimation model based on a transform matrix of received signals and transmitted signals, the transform matrix including parameters related to an amplitude change and phase change of I-path transmitted signals and Q-path transmitted signals by the optical transmitter.
- Supplement 12 The method according to supplement 11, wherein the estimating the IQ imbalance of an optical transmitter on the AC coupled I-path received signals and Q-path received signals includes:
- Supplement 13 The method according to supplement 12, wherein the estimating the IQ imbalance of an optical transmitter on the AC coupled I-path received signals and Q-path received signals based on a training sequence includes:
- Supplement 14 The method according to supplement 13, wherein the calculating the transform matrix according to the synchronized I-path received signals and Q-path received signals and the training sequence includes:
- Supplement 15 The method according to supplement 13, wherein the calculating the transform matrix according to the synchronized I-path received signals and Q-path received signals and the training sequence includes:
- Supplement 16 The method according to supplement 11, wherein the estimating the IQ imbalance of an optical transmitter on the AC coupled I-path received signals and Q-path received signals includes:
- Supplement 17 The method according to supplement 16, wherein the estimating the IQ imbalance of an optical transmitter on the AC coupled I-path received signals and Q-path received signals based on a blind estimation method includes:
- a compensation method for 10 imbalance of an optical transmitter including:
Landscapes
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Physics & Mathematics (AREA)
- Power Engineering (AREA)
- Electromagnetism (AREA)
- Optics & Photonics (AREA)
- Optical Communication System (AREA)
Abstract
Description
I 1 +j*Q 1 =be jθ
the second forming
N denoting a length of the training sequence, i.e. the number of training symbols in the training sequence, and the first calculating
and the reference matrix
by using above formula (2).
and the reference matrix
by using above formula (2), and obtains the matrix C denoted by formula (4) below:
where
denotes the received constellation matrix,
denotes the reference matrix, N denotes the length of the training sequence, (·)r denotes a transposition operation of the matrix, and (·)−1 denotes an inverse operation of the matrix.
a
is obtained.
of the amplitude changes and the difference Δθ=θQ−θI between the phase changes of the I-path transmitted signals and the Q-path transmitted signals obtained according to elements in the transform matrix C and the transform matrix C.
or performs compensation for the phase offset drift by using a matrix
or performs compensation for the amplitude imbalance and the phase offset drift by using the inverse matrix C−1 of the transform matrix C.
Step 1404: at an optical receiver end, the IQ imbalance of the optical transmitter is compensated for the AC coupled I-path received signals and Q-path received signals according to an inverse matrix of the transform matrix; or,
Step 1405: at an optical transmitter end, the I-path transmitted signals and Q-path transmitted signals are pre-compensated according to at least one of a ratio of the amplitude changes of the I-path transmitted signals and the Q-path transmitted signals, a difference between the phase changes of the I-path transmitted signals and the Q-path transmitted signals and the transform matrix, the ratio and the difference being both obtained from the transform matrix.
a fourth estimating unit configured to, for transmitted signals of a non-constant modulus modulation format, calculate the transform matrix by using a radial orientation equalization algorithm according to the AC coupled I-path received signals and Q-path received signals.
where, b and a respectively denote the amplitude changes of the I-path transmitted signals and the Q-path transmitted signals by the optical transmitter, and θI and θQ respectively denote the phase changes of the I-path transmitted signals and Q-path transmitted signals by the optical transmitter.
where, b and a respectively denote the amplitude changes of the I-path transmitted signals and the Q-path transmitted signals by the optical transmitter, and θI and θQ respectively denote the phase changes of the I-path transmitted signals and Q-path transmitted signals by the optical transmitter.
Claims (11)
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
CN201711021004 | 2017-10-27 | ||
CN201711021004.8A CN109728856B (en) | 2017-10-27 | 2017-10-27 | Estimation device and compensation device for IQ imbalance of optical transmitter and electronic equipment |
CN201711021004.8 | 2017-10-27 |
Publications (2)
Publication Number | Publication Date |
---|---|
US20190132183A1 US20190132183A1 (en) | 2019-05-02 |
US10630526B2 true US10630526B2 (en) | 2020-04-21 |
Family
ID=66244448
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US16/163,975 Active US10630526B2 (en) | 2017-10-27 | 2018-10-18 | Estimation apparatus for IQ imbalance of optical transmitter, compensation apparatus for IQ imbalance of optical transmitter and electronic equipment |
Country Status (2)
Country | Link |
---|---|
US (1) | US10630526B2 (en) |
CN (1) | CN109728856B (en) |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2021148954A (en) * | 2020-03-19 | 2021-09-27 | 国立研究開発法人情報通信研究機構 | Optical modulator evaluation technology based on phase recovery |
CN111800198B (en) * | 2020-05-25 | 2021-12-07 | 哈尔滨工业大学(深圳)(哈尔滨工业大学深圳科技创新研究院) | Method and system for separating and monitoring imbalance of transceiver with transparent modulation format |
CN114826845B (en) * | 2022-05-30 | 2024-05-03 | 上海星思半导体有限责任公司 | IQ imbalance estimation method and device and related equipment |
Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20020071506A1 (en) * | 1995-03-09 | 2002-06-13 | Bjorn Lindquist | Slope drift and offset compensation in zero-if receivers |
US20050196176A1 (en) * | 2004-03-08 | 2005-09-08 | Han Sun | Equalization strategy for dual-polarization optical transport system |
US20100303474A1 (en) * | 2009-05-29 | 2010-12-02 | Fujitsu Limited | Digital coherent optical receiver |
US9160586B1 (en) | 2013-07-24 | 2015-10-13 | Marvell International Ltd. | Method and apparatus for estimating and compensating for in-phase and quadrature (IQ) mismatch in a receiver of a wireless communication device |
CN105162533A (en) | 2015-07-24 | 2015-12-16 | 天津大学 | Transmitter amplitude imbalance and phase imbalance measuring method |
CN105610760A (en) | 2016-01-29 | 2016-05-25 | 深圳市极致汇仪科技有限公司 | Detection method of wireless comprehensive testing instrument for IQ unbalance of single carrier QPSK signal |
CN105847198A (en) | 2016-03-15 | 2016-08-10 | 东南大学 | IQ imbalance estimation and compensation method of OFDM-WLAN radio frequency testing system |
Family Cites Families (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP2930867B1 (en) * | 2013-01-25 | 2019-04-24 | Nippon Telegraph and Telephone Corporation | Light-receiving device and phase cycle slip reduction method |
CN106100733A (en) * | 2016-06-14 | 2016-11-09 | 苏州迈奇杰智能技术有限公司 | A kind of domestic optic communication mobile terminal controls energy conserving system |
CN106992816B (en) * | 2016-11-04 | 2019-03-22 | 西安电子科技大学 | A kind of method of photonics wide-band microwave IQ modulation |
CN106850497B (en) * | 2017-01-16 | 2020-05-15 | 中国科学技术大学 | Cascade compensation method in coherent light OFDM communication system |
-
2017
- 2017-10-27 CN CN201711021004.8A patent/CN109728856B/en active Active
-
2018
- 2018-10-18 US US16/163,975 patent/US10630526B2/en active Active
Patent Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20020071506A1 (en) * | 1995-03-09 | 2002-06-13 | Bjorn Lindquist | Slope drift and offset compensation in zero-if receivers |
US20050196176A1 (en) * | 2004-03-08 | 2005-09-08 | Han Sun | Equalization strategy for dual-polarization optical transport system |
US20100303474A1 (en) * | 2009-05-29 | 2010-12-02 | Fujitsu Limited | Digital coherent optical receiver |
US9160586B1 (en) | 2013-07-24 | 2015-10-13 | Marvell International Ltd. | Method and apparatus for estimating and compensating for in-phase and quadrature (IQ) mismatch in a receiver of a wireless communication device |
CN105162533A (en) | 2015-07-24 | 2015-12-16 | 天津大学 | Transmitter amplitude imbalance and phase imbalance measuring method |
CN105610760A (en) | 2016-01-29 | 2016-05-25 | 深圳市极致汇仪科技有限公司 | Detection method of wireless comprehensive testing instrument for IQ unbalance of single carrier QPSK signal |
CN105847198A (en) | 2016-03-15 | 2016-08-10 | 东南大学 | IQ imbalance estimation and compensation method of OFDM-WLAN radio frequency testing system |
Non-Patent Citations (2)
Title |
---|
Nguyen et al., "Blind Adaptive Transmitter IQ Imbalance Compensation in M-QAM Optical Coherent Systems", IEEE ICC 2016-Optical Networks and Systems, 6 pgs. |
Nguyen et al., "Blind Adaptive Transmitter IQ Imbalance Compensation in M-QAM Optical Coherent Systems", IEEE ICC 2016—Optical Networks and Systems, 6 pgs. |
Also Published As
Publication number | Publication date |
---|---|
US20190132183A1 (en) | 2019-05-02 |
CN109728856A (en) | 2019-05-07 |
CN109728856B (en) | 2021-12-31 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US10630526B2 (en) | Estimation apparatus for IQ imbalance of optical transmitter, compensation apparatus for IQ imbalance of optical transmitter and electronic equipment | |
US9729232B2 (en) | Method and device for estimation of chromatic dispersion in optical coherent communication | |
EP3094037A1 (en) | Clock recovery method, device and system and computer storage medium | |
US10345673B2 (en) | Bias control apparatus and method of modulator of optical transmitter and optical transmitter | |
US20170250792A1 (en) | Signal transmission apparatus, carrier phase recovery apparatus and method | |
JP6191416B2 (en) | Frequency offset estimation circuit and frequency offset estimation method | |
CN103339883A (en) | Signal processing circuit, signal processing method, optical receiver and optical communication system | |
EP3029512A1 (en) | Spectral inversion detection for polarization-division multiplexed optical transmission | |
Jensen et al. | Robust computation of error vector magnitude for wireless standards | |
US10404380B2 (en) | Compensation apparatus for offset drift, received signal recovery apparatus and receiver | |
US11329724B2 (en) | State of polarization tracking recovery method and apparatus | |
US20180123700A1 (en) | Method and apparatus for estimating polarization dependent loss and receiving device | |
EP3096469A1 (en) | Chromatic dispersion measurement method and device and digital coherent receiver | |
US11563496B2 (en) | Phase response measurement method and apparatus | |
CN104052693B (en) | Frequency error estimation unit and method, frequency error compensation device and optical receiver | |
US20170227585A1 (en) | Harmonic distortion separation method, nonlinear character determination method and apparatus and system | |
US10903911B2 (en) | Apparatus and method for estimating polarization skew | |
US20180102838A1 (en) | Measuring apparatus and method of frequency response characteristic imbalance of optical receiver | |
CN103873416A (en) | EVM (Error Vector Magnitude) phase estimating and compensating method | |
WO2023061213A1 (en) | Optical signal skew extraction method and apparatus, electronic device, and storage medium | |
US10574350B2 (en) | Method and apparatus for estimating direct current bias of optical modulator and receiver | |
US20170104577A1 (en) | Estimating apparatus for bias drift of transmitting end modulator, compensating apparatus and receiver | |
JP2019161355A (en) | Optical receiver | |
US10734950B2 (en) | Phase noise compensation apparatus and method and receiver | |
US10177844B2 (en) | Measurement method and apparatus for a residual direct-current component and system |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
FEPP | Fee payment procedure |
Free format text: ENTITY STATUS SET TO UNDISCOUNTED (ORIGINAL EVENT CODE: BIG.); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY |
|
AS | Assignment |
Owner name: FUJITSU LIMITED, JAPAN Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:FAN, YANGYANG;TAO, ZHENNING;SIGNING DATES FROM 20181011 TO 20181012;REEL/FRAME:047260/0109 |
|
STPP | Information on status: patent application and granting procedure in general |
Free format text: DOCKETED NEW CASE - READY FOR EXAMINATION |
|
STPP | Information on status: patent application and granting procedure in general |
Free format text: NON FINAL ACTION MAILED |
|
STPP | Information on status: patent application and granting procedure in general |
Free format text: RESPONSE TO NON-FINAL OFFICE ACTION ENTERED AND FORWARDED TO EXAMINER |
|
STPP | Information on status: patent application and granting procedure in general |
Free format text: NOTICE OF ALLOWANCE MAILED -- APPLICATION RECEIVED IN OFFICE OF PUBLICATIONS |
|
STCF | Information on status: patent grant |
Free format text: PATENTED CASE |
|
MAFP | Maintenance fee payment |
Free format text: PAYMENT OF MAINTENANCE FEE, 4TH YEAR, LARGE ENTITY (ORIGINAL EVENT CODE: M1551); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY Year of fee payment: 4 |